A boat which has a speed of 5 km/hr in still water crosses a river of width 1 km along the shortest possible path in 15 minutes. The velocity of the river water in km/hr is

A boat which has a speed of 5 km/hr in still water crosses a river of

1.	A boat which has a speed of 5 km/hr in still water crosses a river of width 1 km along the shortest possible path in 15 minutes. The velocity of the river water in km/hr is
Answer» Solution :Resultant VELOCITY = `(1km)/((15//60)h) = 4 km//h` If v is velocity of RIVER, then `v^(2)+4^(2) = 5^(2) rArr v = sqrt(25-16) = 3 km//h`